Numerical Simulation of Pressure Drop Through a Rotating Plenum Fan

In this paper the numerically determined pressure increase (ΔP) versus volumetric flow rate (CFM) curve at a given fan speed for a plenum fan is compared to experimental data. The simulations were carried out using a rotating fan blade section and a fixed inlet and outlet plenum with a three-dimensional tetrahedral computational mesh. The objective of this work is to assess the feasibility of approximating a 36” plenum ΔP-CFM fan curve using a low order computational approach and thereby assessing the effectiveness of using such an approach as a real time design tool. The measures of success of this work include demonstrating the ability to capture pertinent characteristics of the fan curve such as slope and roll-off of the ΔP-CFM curve. It was found that a fairly high resolution was required near the fan blade section in order to better approximate the ΔP-CFM curve. This higher resolution greatly increased the runtime. In addition, including a k-e turbulent model improved the pressure drop characteristics as compared having no turbulence model. It is hoped that an approach such as this will be adopted in the real time design and manufacture of plenum fans.